Home Inspection State Practice Exam 2026 - Free Home Inspection Practice Questions and Study Guide

Combustion air should not be drawn from inside a building when the building is constructed using tight construction methods. In tightly constructed buildings, the air exchange between the interior and exterior is significantly reduced. This can lead to inadequate replacement air for combustion appliances, as these systems require a certain amount of air to operate efficiently and safely.

Insufficient combustion air can result in incomplete combustion, which not only reduces the efficiency of the heating system but can also produce dangerous levels of carbon monoxide. In contrast, buildings that are not tightly sealed can allow for better air exchange, making it safer for combustion appliances to draw air from inside.

While there are scenarios mentioned in the other options that could affect the combustion air supply, none are as critical as the tight construction aspect. Even if there is sufficient outdoor air supply or if the heating system is over-ventilated or outdated, the fundamental principle of combustion air needs to be addressed specifically, ensuring that adequate and safe air supply is provided for combustion processes.